The most valuable feature for us is the portability of the VM itself. I've dealt with enough physical servers to see the benefit of having a layer of abstraction between Windows or Linux or whatever software is running on top of the hypervisor. It provides flexibility and manageability by abstracting the physical dependencies from the physical hardware.
Improvements to My Organization
It's allowed us to consolidate 150 physical servers down to six servers with 150 VM's running on top. That's the biggest impact to our environment.
Room for Improvement
The web client needs a lot of work. Unless they replace the C# client with something better, they're going to have issues. Without a better management interface, they're going from a great system to a very poor one.
Use of Solution
I've been using it since version 3.5, which was 2009, so about seven years now.
We haven't had issues with deploying it.
It's definitely stable as I've seen ESXI servers up for 1000 days before a reboot. You can go with management services without attached the VM's.
I started in a very small environment with two hosts with 20 VM's and now we have 25 hosts spread across data centers and branch offices and much bigger clusters. The scalability is definitely there.
Customer Service and Technical Support
I've had some issues with support recently. I was lucky enough to get accepted into the vSphere Beta program so I got more direct contact about my issues, but their tech support has not been as good as it used to be.
That depends on your definition of complex. It takes some time to wrap your head around the concept of virtualization. But it gets simpler, especially as you set up from scratch.
Pricing, Setup Cost and Licensing
Make sure you're using the right licenses because VMware licensing is a little bit complex. In my previous job, I ran into an issue where I wanted to expand our cluster from three hosts to four hosts, but we couldn't do it because my boss had bought a vCenter Foundation license and it only permitted three hosts. It's one of those little surprises that you can find yourself in. Just pay attention and make sure you are buying the right system that's going to scale to what you need as far as licensing goes.
Other Solutions Considered
It was already in place when I came into my position. I believe it was chosen because it's the best on the market. Hyper-V isn't at feature-parity with vSphere.
It's just made my life so much better as far as being able to move servers around and perform firmware updates during the middle of the day. I love that.